AB1685 ANTI-DFS70: ARE THEY HELPFUL WHEN ASSESSING FOR SYSTEMIC AUTOIMMUNE RHEUMATIC DISEASES?
Authors: D. Galarza, I. Carrion, C. Veloza, H. Sirera Perello, T. Salman-Monte, A. Pros, E. Villegas, J. Eguía, C. Pérez, J. Monfort
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Autoantibodies against DFS70 (dense fine speckles 70) antigen (anti-DFS70) are purported to rule out systemic autoimmune rheumatic diseases (SARD) when detected in the absence of other SARD-related antibodies. They are recognized using indirect immunofluorescence (IIF) and are a common finding among antinuclear antibodies (ANA)-positive healthy individuals. Data published so far highlights the negative association between anti-DSF70 and SARD. <h3>Objectives</h3> Describe the characteristics of a cohort of anti-DFS70+ patients and its relationship with the presence of SARD and analyze the existence of other variables that could be related to SARD and might be used as clinical prediction tools. <h3>Methods</h3> Retrospective study of anti-DFS70+ patients at Hospital del Mar (Bcn, Spain) in 2021 and 2022. Demographic, clinical and biological data were collected. Presence of anti-DFS70 was determined by immunoblot using EUROLine-EUROIMMUN kit, which allows qualitative in vitro determination of human autoantibodies of IgG isotype. Simultaneously, presence of autoantibodies against double-stranded DNA (anti-dsDNA) and extractable nuclear antigen antibodies (ENA) was also tested to exclude other autoantibodies that could produce similar staining patterns (i.e., AC-1 or AC-1 with AC-4,5). A descriptive and correlations statistical analysis was performed using SPSS 23 IBM®. <h3>Results</h3> Sera from 85 ANA+ patients with a DFS IIF pattern were tested for anti-DFS70. 52 patients tested positive and were included: 10 males and 42 females. Mean age to first anti-DFS70+ determination was 40.67 ±16.99 years. Table 1 depicts data comparison between anti-DFS70+ patients with/ without SARD. No SARD was found in 44 patients (84.6%). From 8 patients with SARD, 2 tested positive for other autoantibodies. A correlation was found between higher ANA titers and presence of SARD. No other significant correlation was found. <h3>Conclusion</h3> Our data suggest that in a population of ANA-positive patients being studied for SARD, the presence of anti-DFS70, even at moderate to high titer, may be considered a reassuring result regarding the negative association with SARD. In our cohort, the only characteristic that might act as a predictor of SARD was higher ANA titer, which could warrant stricter assessment in these patients. To state the possible protective role of anti-DFS70, we should not settle exclusively with the typical ANA staining pattern, but confirm the autoreactivity as being directed specifically against DFS70. Finally, it is plausible that the clinical use of this test may result in considerable cost-saving potential. <h3>References</h3> [1]Miyara M, Albesa R, Charuel JL, et al. Clinical phenotypes of patients with anti-DFS70/LEDGF antibodies in a routine ANA referral cohort. Clin Dev Immunol 2013; 2013:703759. [2]Ochs RL, Mahler M, Basu A, et al. The significance of autoantibodies to DFS70/LEDGFp75 in health and disease: integrating basic science with clinical understanding. Clin Exp Med 2016;16:273-93. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> David Galarza Speakers bureau: FAES FARMA, Irene Carrion: None declared, Camilo Veloza: None declared, Helena Sirera Perello: None declared, Tarek Salman-Monte: None declared, Ana Pros: None declared, Eduardo Villegas: None declared, Jorge Eguía: None declared, Carolina Pérez Speakers bureau: Abbvie, Jordi Monfort: None declared.